Research On The Precision Hard Turning Of Thin-Wall Bearing Rings

Hard turning is a key technology to manufacture bearing rings with high precision and efficiency.However,bearing rings with high hardness become thinner-walled,and require high dimensional accuracy and high surface quality.How to ensure the tool life,high surface quality and chip breaking automatically becomes the main problems of bearing manufacturing industry.Therefore,this paper considered the hard turning of thin-wall bearing rings as the research object,designed the micro chamfer on the cutting edge.Through simulation analysis and experimental research,the cutting force,cutting temperature and the formation of saw-tooth chips were studied,effects of chamfer parameters on cutting force and temperature were verified.Further,the influence factors of surface integrity,tool life and tool wear mechanism were analyzed,and the critical conditions for the transition from banded chips to sawtooth chips were explored.The main research works are as follows:(1)The GCr15 bearing rings were selected as the workpiece material.The material,geometry of cutting tool and the cutting edge chamfer of insert were selected and designed.Further,a 2D finite element model was established.The cutting force,cutting temperature and formation of saw-tooth chips were studied,and the effects of chamfer parameters on cutting force and cutting temperature were analyzed.(2)Precision hard turning experiments of GCr15 bearing rings with PcBN tools were performed,and the effects of chamfer parameters on cutting force and chip deformation were verified and further studied.The critical conditions for the transition from banded chips to saw-tooth chips were explored.(3)The surface integrity experiments of GCr15 bearing rings with PcBN tools were carried out,and the effects of chamfer parameters and cutting parameters on the surface roughness,surface residual stress and subsurface residual stress distribution were investigated.(4)The tool wear experiments of hard-turning GCr15 bearing rings with PcBN tools were carried out.A rapid tool life assessment method was used to study the effects of chamfer parameters on tool life,and the tool wear pattern and mechanism of PcBN tools in hard turning of GCr15 bearing rings were studied.